Flexible intelligent sensing is a burgeoning field of study that covers various disciplines, including but not restricted to chemistry, physics, electronics and biology. However, the widespread use of flexible sensors remains challenging because of certain constraints, such as limited stretchability, poor biocompatibility, low responsivity, and the complexity of multifunctional integration. Conductive hydrogels with remarkable material properties are presently in the spotlight of flexible sensing. In the pursuit of high-performance and “green” conductive hydrogel-based sensors, cellulose is a promising candidate owing to its renewability, low cost, appealing mechanical properties, easy modification and other functional characteristics. Herein, cutting-edge progress in the fabrication of conductive cellulose hydrogels (CCHs) using cellulose and cellulose derivatives in terms of structural features, preparation approaches, functional properties, applications, and prospects for sensors is comprehensively summarized. The correlation between CCHs performances, reinforcement strategies and sensor properties is highlighted to gain insight into the process of developing smart sensors by utilizing CCHs. Besides, the state-of-the-art advances of CCHs toward emerging wearable sensors, including strain/pressure sensors, temperature sensors, humidity sensors, and biosensors, are systematically discussed. Finally, potential challenges and future outlooks of such attractive CCH-based flexible sensors are presented, providing valuable information for the development of next-generation cellulose-based electronic devices.